1. Field
Example embodiments relate to methods that may correct read errors of data of memory devices. Also, example embodiments relate to apparatuses and/or methods that may correct errors of read data of multi-level cell (MLC) memory devices or multi-bit cell (MBC) memory devices.
2. Description of Related Art
Recently, a multi-level cell (MLC) memory device that may store data of two or more bits in a single memory cell has been proposed in response to a need for higher integration of memory. The MLC memory device may also be referred to as a multi-bit cell (MBC) memory. However, as the number of bits programmed in the single memory cell increases, reliability may deteriorate and a read-failure rate may increase. To program ‘m’ bits in the single memory cell, any one of 2m threshold voltages may need to be generated in the memory cell. Threshold voltages of memory cells where the same data is programmed may generate a distribution within a predetermined range due to the minute electrical characteristic difference between the memory cells. Each threshold voltage distribution may correspond to one of 2m data values generated by ‘m’ bits.
However, since a voltage window for a memory device may be limited, a distance between 2m distributions of threshold voltages between adjacent bits may decrease as ‘m’ increases, and the distributions may be overlapped as the distance between the distributions decreases. When the distributions are overlapped, the read-failure rate may increase.
As the MLC memory device has been widely and recently used, error control codes or error control coding or error correction codes (ECC) that may detect an error occurring when storing and reading the data and correct the detected error have been actively used.
When the data is maintained for a long time, due to a lateral movement of a charge which may be caused by an electrostatic attractive force between the charge stored in the memory cell and the charge stored in an adjacent cell, a charge trap memory including a multi-level cell may need to efficiently correct a read error.